ENDOR study of the intermolecular interactions of bis( O , O ′‐dialkyldithiophosphate)copper(II) with diamagnetic matrices

Polycrystalline samples of dithiophosphate (dtp) complexes Cu II [Cu(R 2 dtp) 2 ], magnetically diluted in Ni (R 2 dtp) 2 , Pd(R 2 dtp) 2 or Pt(R 2 dtp) 2 matrices (R = CH 3 , C 2 H 5 or i ‐C 3 H 7 ) were studied. ENDOR transitions for the 1 H and 31 P nuclei belonging to the copper(II) dithiophosphate molecules were recorded for the Cu/Ni(Me 2 dtp) 2 , Cu/Ni(Et 2 dtp) 2 , Cu/Pd(Et 2 dtp) 2 , Cu/Pt(Et 2 dtp) 2 and Cu/Ni( i ‐Pr · dtp) 2 samples. In the case of Cu/Pd(Me 2 dtp) 2 , Cu/Pt(Me 2 dtp) 2 , Cu/Pd( i ‐Pr · dtp) 2 and Cu/Pt( i ‐Pr · dtp) 2 , in addition to the above‐mentioned ENDOR transitions, 1 H and 31 P transitions were recorded for nuclei which belong to the dithiophosphate molecules of the diamagnetic matrix. It was established that the crystal packing of the molecules of the diamagnetic matrices favours intermolecular interactions. Spin density transfer for the molecules of the diamagnetic matrices was observed only in the case when Cu(R 2 dtp) 2 is included in crystal lattices having only one molecule in the unit cell ( Z = 1). The coplanar arrangement (for Z = 1) of the chelate rings from neighbouring paramagnetic and diamagnetic molecules favoured the transfer of the spin density on the 31 P nuclei of the latter. The high value of the isotropic hyperfine splitting constant in the 31 P nuclei from the diamagnetic molecule is explained by the weak overlapping of orbitals from neighbouring molecules. The intermolecular interactions leading to the occurrence of ENDOR transitions in the 1 H nuclei which belong to the molecules of the diamagnetic matrix are also discussed.